The present invention relates to damper structures and more specifically to the reduction of low frequency noise in damper structures.
Air flow structures such as dampers are subject to self-generated noise which is a function of the velocity and pressure of the delivered air as well as the structural details of the air distribution system. Various techniques have been employed to reduce noise generation. For example, air distribution systems have been lined with sound-absorbing materials, and diffusers in the form of perforate plates have been placed across the flow paths. These techniques have met with varying success. An excessive thickness of sound-absorbing materials is necessary to attenuate low frequency noise; perforate plates can cause excessive pressure drops and the low frequency noise can be reestablished in the recombined flow. Further, these techniques do not address the problem of noise production resulting from flow over the edges of sheet metal members.